Mono Reissues and the Conical Stylus

I think there is some general confusion about the bridging concept used to sum the stereo signal to add the lateral movement and null the vertical and a cartridge that only picks up information in the lateral plane.    My take is that if the coils remain oriented at a 45º angle to the record and then wired in series for mono then it is a stereo cartridge wired for mono and it doesn't matter if it if done internally or externally.  If however the same parts are used for a mono cartridge and the coil is oriented so there is only pickup in the lateral plane, then it is a mono cartridge.  In this case there would be only be windings for pickup in the lateral plane and the windings at 90º to that plane would not be used / wound.  

As for the "U" shape discussion I think it leads to a bunch of confusion.  I have yet to see a cutting stylus with anything other than a "V" shape with the angle of the v being slightly less than 90º.  Whether this cutting edge cuts with information in just the lateral plane (mono) or in both the lateral and vertical plane (stereo) does not matter and the groove cross section will always be a V.  The only way a groove with a rounded bottom to resemble a "U" could be done would be with a rounded point cutter and I have never seen anything like that and even if it existed, it would do a very poor job of cutting.

dave

Dave, are you saying that late 1940's to late 1950's mono records are cut with the same V shaped groove as stereo records?

That is my understanding.  I just looked at a 1955 London ffrr  (Ted Heath ant the London Palladium) and the groove is a V.  The bottom does have a slight radius.  A stereo cutting stylus specified by Ortophon has a 3-4µm radius which would explain that but that is still a fraction of the radius of even the smallest conical.  

dave

Dave,

I'm thinking that your London LP should be a microgroove pressing. I suppose technically you're correct, that the shape of the groove is a V looking shape however that groove opening is wider than the later stereo cut grooves. In fact, the grooves on LP's started out wider and progressively got more narrow over time. When Columbia introduced their microgroove pressings, manufacturers complained about how narrow the grooves were in comparison to the earlier records (i.e. 78's)
As Lewm mentioned, the U shape description is just a vernacular term for specifying the difference in dimensions in order to clarify the point being made. Mono cartridge makers will use a nude conical stylus because of those earlier groove dimensions.

Dave, You wrote, "My take is that if the coils remain oriented at a 45º angle to the record and then wired in series for mono then it is a stereo cartridge wired for mono and it doesn't matter if it if done internally or externally. If however the same parts are used for a mono cartridge and the coil is oriented so there is only pickup in the lateral plane, then it is a mono cartridge. In this case there would be only be windings for pickup in the lateral plane and the windings at 90º to that plane would not be used / wound."
That is also what I and many others have been saying here and elsewhere.  What I wondered about is whether from a purist standpoint, does the true mono cartridge offer us a level of performance in the mono mode that cannot be had via the bridged stereo approach?  I guess that if you use bridging, then cancellation would be imperfect to the degree that the two channels of the cartridge are not perfectly matched, which probably never happens.